Standard procedures used for fabrication of polymeric objects consist of polymerization, isolation, purification of synthesized polymer followed by shaping polymeric material into a desired form. However, there is growing an interest in processes with all these steps proceeding parallel. Apparently, parallel synthesis of macromolecules and their self-assembly into desired objects is less time consuming and more energy efficient. Recent studies proved that this way could be used for fabrication of nano- and microobjects with accuracy not attainable in any other way.
We developed a method (based on dispersion polymerization of lactides and epsilon-caprolactone) suitable for direct synthesis of microspheres. In this paper there will presented results of studies on the mechanism of formation of polyester microspheres and on the post-synthesis treatment allowing formation of particles with controlled degree of crystallinity.
According to developed method the microspheres with diameters from 0.5 to 7 mm and with narrow diameter polydispersity were obtained. Molecular weight of polymers in synthesized microspheres also could be controlled. The second method leading to particles is based on synthesis of block copolymers composed of biodegradable polyester block and hydrophilic blocks of polyglycidol and poly(ethylene oxide), followed by assembling the copolymers into nanoparticles. Diameters of formed nanoparticles could be varied, depending on molecular weight of hydrophobic (polyester) and hydrophilic blocks, from 22 to 60 nm. Their diameter polydispersity was narrow (Dw/Dn <1.2). Procedures suitable for loading of the mentioned above microspheres and nanoparticles with bioactive compounds will be discussed.
Strategies suitable for using microspheres and nanoparticles as building blocks of materials porous on nano- and micrometer level will be discussed.
This work was supported by the State Committee of Scientific Research, grant No. 05/PBZ-KBN-082/2002/06.